Process of preparing secondary-battery plates



STATES PA'rnN'r @rricn.

ABRAHAM V. MESEROLE, OF NEXV YORK, N. Y., ASSIGNOR TO THE RlVER- AND RAIL ELECTRIC LIGHT COHPANY, OF WEST VIRGINIA.

PROCESS OF PREPAFHNG SECONDARY-BATTERY PLATES.

EPEGZFICATION forming part of Letters Patent No, 359,876, dated March 22, 1887.

Application filed November 18, 1886.

To all whom it 711.54g concern.-

Beitk no w n that LABRAHAM V. Mnsnuonn,

a citizen of the United States, residingin the city, county, and State of New York, haveinvented a new and useful Improvement in Processes of Preparing Secondary-Battery Plates, which I desire to protect by Letters Patent'of the United States, and of which the following is a specification, this application being designated by the letter A.

My invention relates to that class of batteries in which electrical energy may be stored for future redevelopment and use, and has particular reference to the formation of plates in what is known as the Plant form of these batteries. As is well known, the formative electrolytic process to which the plates for batteries of this kind are subjected is much accelerated if the plates are first thoroughly cleaned of all organic and mineral impurities. I have found that the best surface for receiving electrolytic action is that in which the metallic crystals of the plate arerelievedfrom all foreign substances, and also from amorphous particles of the metal itself, such as are usually present in the porous cavities between the crystals, so that the surfaces of the crystals may be directly presented to the action of the liquid.

My present invention consists in a treatment having for its object the bringing about of this condition of the plates. The impurities which it is necessary to remove being both organic and mineral, it is desirable to use solutions specially adapted to removei mpurities of those two kinds, IQSPBCtlVBlY. For grease and other organic impurities alkalies are the best solvents, while mineral matter is best removed by acids. As the organic impurities are likely to be on the outer surface of the plate, it is generally best to cause the alkali treatment to precede the acid treatment. I first place the plates in an alkali bath, and I find that the action of the chemical is considerably intensi- 5 fied and accelerated by distributing the plates into pairs and passing through them and the liquid an electrical current, the polarity of which I reverse at intervals for the purpose of permitting each plate in turn to be acted upon by the liberated oxygen. It should be observed that the reversal of the current is merely a Serial XofiElOfiUO. (No specimens.)

convenient expedient. Ifthe plates were put in the bath singly, it would only be necessary to pass the current in one direction, making the plates undergoing the operation the oxygen 5 5 or positive pole. After treating the plates in this manner long enough to cleanse their surfaces, I place them in a dilute acid bath, the efficiency of which is also greatly increased by a similar use of electric currents. I use dilute 6o acid for the reason that my object is not to dissolve the body of the plate or corrode it, but

merely to remove such foreign and disintegrated mineral particles as may have lodged in the pores of the metal. After removal from 6 5 the acid bath the plates should be thoroughly cleansed, to free them from any traces of acid and to prevent possible local action being set up in the plates thereby. This cleansing may be accomplished in any desired manner. I find the most practical method to be to return the plates to the'alkali bath for a short period, afterward washing them with pure water.

The above explanation of the efficiency of my process-to wit, the existence of different kinds of impurities requiring the application of different solvents for their removal-is the only one I am at present able to give. There are doubtless obscure chemical reactions induced by it, to which the results are in part due, the exact nature of which I am at present unable to set forth. I know, however, from many actual trials, that a plate which has been subjected to the treatment described will be found to be thoroughly freed from impurities, 8 5 both organic and mineral, the amorphous particles of metal between its surface crystals will have been removed, and the faces of the crystals sharply exposed to the action of the elec trolytic fluid.

In case any spongy lead has been formed upon the plates by the alkali treatment I brush it oh, its connection with the plate being too slight to give it any practical value. In fact, where such spongy deposits are left upon the plates, I find that they are generally caused to scale off by the oxidation of the crystals beneath them, and therefore hinder rather than advance the formation of the plates.

lVhile I have found that electric currents are very useful in connection with the alkali and acid baths, I wish it understood thatl do not limit myself to the use of such currents, but claim, broadly, the alternating succession of alkali and acid treatment. 1\Ioreover,while I find it best to use the alkali first, I do not limit myself to that order of treatment,an acid bath followed by an alkali bath being equally within my invention.

I am aware that it has been heretofore proposed to corrode the surface of secondary-battery plates. This process, however, I do not claim or practice, and I consider it injurious to the plates when used, and of no practical advantage. My invention is confined to the use of a dilute acid solution of a strength insufficient to attack the crystalline structure of the plates. The effect of my process on the plate is clearly shown by the microscope, the crystals being revealed in clean-cut forms on its surface.

I claim 1. The improved process of preparing plates for secondary batteries, which consistsin treating them alternately with alkali'and dilute acid solutions under electrical. action.

2. Theimproved process of preparing plates for secondary batteries, which consists in p1acing them in baths of alkali and dilute acid solutions alternately and passing through them and the baths a current of electricity, sub-' ABRAHAM v. MEsnRoLE.

W'ilnesses:

M. H. PHELPS, Gno. L. WRIGHT. 

